Produced good leather trousers (5)
I believe the answer is:
begat
'produced' is the definition.
(I've seen this in another clue)
'good leather trousers' is the wordplay.
'good' becomes 'g' (abbreviation).
'leather' becomes 'beat' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'trousers' means one lot of letters goes inside another (to trouser can mean to steal or take).
'g' inserted inside 'beat' is 'BEGAT'.
Can you help me to learn more?
(Other definitions for begat that I've seen before include "Generated" , "Produced new life" , "Fathered (biblically)" , "Sired" .)