From lover, a heartless lie leads to trouble (10)
I believe the answer is:
aficionado
'from lover' is the definition.
I can't tell whether this defines the answer.
'a heartless lie leads to trouble' is the wordplay.
'heartless' suggests removing the centre.
'lie' becomes 'fiction' (I've seen this before).
'leads' means one lot of letters go next to another.
'to trouble' becomes 'ado' (both can mean bother or commotion).
'fiction' with its middle taken out is 'ficion'.
'a'+'ficion'+'ado'='AFICIONADO'
(Other definitions for aficionado that I've seen before include "Admirer" , "Expert person" , "Devotee" , "Fan; enthusiast" , "freak" .)