Blows up as former partner criticises getting custody of daughter (7)
I believe the answer is:
expands
'blows up' is the definition.
('expand' can be a synonym of 'blow up')
'former partner criticises getting custody of daughter' is the wordplay.
'former partner' becomes 'ex' (an ex-partner).
'criticises' becomes 'pans' (pan can mean to criticise severely).
'getting' indicates putting letters inside.
'custody of daughter' becomes 'd' (I can't explain this - if you can you should believe this answer much more).
'pans' going around 'd' is 'pands'.
'ex'+'pands'='EXPANDS'
'as' acts as a link.
Can you help me to learn more?
(Other definitions for expands that I've seen before include "gets bigger" , "Becomes larger" , "Enlarges" .)