After losing heart, boy shot back for a kiss (4)
I believe the answer is:
snog
'kiss' is the definition.
(I've seen this before)
'after losing heart boy shot back' is the wordplay.
'after losing heart' says to hollow out the word (remove centre letters).
'boy' becomes 'son' (male child).
'shot back' becomes 'og' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'son' with its middle taken out is 'sn'.
'sn'+'og'='SNOG'
'for a' acts as a link.
Can you help me to learn more?
(Other definitions for snog that I've seen before include "Cuddle, kiss (slang)" , "Indulge in amorous activity" , "Kiss and cuddle (sl.)" , "Pet" , "Amorously kiss" .)