A name hair product for sweetheart (5)
I believe the answer is:
angel
'sweetheart' is the definition.
(both are terms of endearment)
'a name hair product' is the wordplay.
'name' becomes 'n' (common abbreviation e.g. on forms).
'hair product' becomes 'gel' (hair gel).
'a'+'n'+'gel'='ANGEL'
'for' is the link.
(Other definitions for angel that I've seen before include "Heavenely messenger" , "Guardian spirit; theatre investor" , "Cloud resident?" , "Top D [DECORATION]" , "Word linking cake and fish" .)