Account for former partner of homely aspect (7)
I believe the answer is:
explain
'account for' is the definition.
(I've seen this before)
'former partner of homely aspect' is the wordplay.
'former partner' becomes 'ex' (an ex-partner).
'of homely aspect' becomes 'plain' (plain can mean homely or simple).
'ex'+'plain'='EXPLAIN'
(Other definitions for explain that I've seen before include "Describe" , "Elucidate, clarify" , "Expound" , "Make intelligible and account for" , "offer clarification" .)