Warm arms going round (4)
I believe the answer is:
snug
'warm' is the definition.
(thesaurus)
'arms going round' is the wordplay.
'arms' becomes 'guns ' (gun is a kind of arm).
'going round' is a reversal indicator.
'guns' backwards is 'SNUG'.
(Other definitions for snug that I've seen before include "Comfortable -- small secluded room" , "Bar-parlour" , "Compact" , "Intimate" , "Bar parlour - comfortably placed" .)