Reformatting text file using awk and cut as a one liner - bash

Question

Data:
CHR SNP BP A1 TEST NMISS BETA SE L95 U95 STAT P
1 chr1:1243:A:T 1243 T ADD 16283 -6.124 0.543 -1.431 0.3534 -1.123 0.14
Desired output:
MarkerName P-Value
chr1:1243 0.14
The actual file is 1.2G worth of lines like the above
I need to strip the 2nd column of the text past the 2nd colon and then paste this to the final 12th column and give it a new header.
I have tried:
awk '{print $2, $12}' | cut -d: -f1-2
but this removes the whole line after the colons and I want to keep the "p" column
I outputted this to a new file and then pasted it onto the P-value column using awk but was wondering if there was a one-liner method of doing this?
Many thanks

Answer 1

My comment in more understandable form:
$ awk '
BEGIN {
print "MarkerName P-Value" # output header
}
NR>1 { # skip the funky first record
split($2,a,/:/) # split by :
printf "%s:%s %s\n",a[1],a[2],$12 # printf allows easier output formating
}' file
Output:
MarkerName P-Value
chr1:1243 0.14

Answer 2

EDIT: Adding one more solution here, since OP mentioned my first solution somehow didn't work for OP but it worked fine for me, as an alternative adding this here.
awk '
BEGIN{
print "MarkerName P-Value"
}
FNR>1{
match($2,/([^:]*:){2}/)
print OFS substr($2,RSTART,RLENGTH-1),$NF
}
' Input_file
With shown samples, could you please try following. You need not to use cut with awk, awk could take care of everything within itself.
awk -F' +|:' '
BEGIN{
print "MarkerName P-Value"
}
FNR>1{
print OFS $2":"$3,$NF
}
' Input_file
Explanation: Adding detailed explanation for above.
awk -F' +|:' ' ##Starting awk program from here and setting field separator as spaces or colon for all lines.
BEGIN{ ##Starting BEGIN section of this program from here.
print "MarkerName P-Value" ##Printing headers here.
}
FNR>1{ ##Checking condition if line number is greater than 1 then do following.
print OFS $2":"$3,$NF ##Printing space(OFS) 2nd field colon 3rd field and last field as per OP request.
}
' Input_file ##Mentioning Input_file name here.

Answer 3

$ awk -F'[: ]+' '{print (NR==1 ? "MarkerName P-Value" : $2":"$3" "$NF)}' file
MarkerName P-Value
chr1:1243 0.14

Answer 4

Sed alternative:
sed -En '1{s/^.*$/MarkerName\tP-Value/p};s/([[:digit:]]+[[:space:]]+)([[:alnum:]]+:[[:digit:]]+)(.*)([[:digit:]]+\.[[:digit:]]+$)/\2\t\4/p'
For the first line, substitute the full line for the headers. Then, split the line into 4 sections based on regular expressions and then print the 2nd subsection followed by a tab and then the 4th subsection.