Girl embracing first of regular soldiers (4)
I believe the answer is:
army
'soldiers' is the definition.
(group of soldiers)
'girl embracing first of regular' is the wordplay.
'girl' becomes 'amy' ().
'embracing' indicates putting letters inside.
'first of regular' becomes 'r' (ast letter of 'regular').
'amy' going around 'r' is 'ARMY'.
(Other definitions for army that I've seen before include "A defence force" , "Multitude" , "Collective term for caterpillars" , "fighters" , "Horde" .)