Lover of old paintings picked up more (5)
I believe the answer is:
extra
'more' is the definition.
(I've seen this before)
'lover of old paintings picked up' is the wordplay.
'lover of old' becomes 'ex' (an ex-lover).
'paintings' becomes 'art' (painting is a type of artwork).
'picked up' shows that the letters should be reversed in order.
'art' written backwards gives 'tra'.
'ex'+'tra'='EXTRA'
(Other definitions for extra that I've seen before include "more than is necessary" , "There's more" , "Supplemental" , "eg Wide; additional" , "walk-on part" .)