Girl's name for my regiment (4)
I believe the answer is:
myra
'girl's name' is the definition.
(I've seen this before)
'my regiment' is the wordplay.
'regiment' becomes 'RA' (Royal Artillery).
'my'+'ra'='MYRA'
'for' acts as a link.
(Other definitions for myra that I've seen before include "Woman's name, anagram of army" , "- - Breckenridge (novel)" , "Girl" , "Dame --- Hess; Vidal's Breckinridge" , "Girl's name" .)