Love to hand one on (7)
I believe the answer is:
passion
'love' is the definition.
(I know that love can be written as passion)
'hand one on' is the wordplay.
'hand' becomes 'pass' (synonyms).
'one' becomes 'i' (Roman numeral).
'pass'+'i'+'on'='PASSION'
'to' acts as a link.
(Other definitions for passion that I've seen before include "Ardour, fervour" , "Great emotion" , "Rage" , "thing one really cares about" , "Intense emotion, anger or love" .)