In favour of turning in coalmine dividend (6)
I believe the answer is:
profit
'dividend' is the definition.
(thesaurus)
'in favour of turning in coalmine' is the wordplay.
'in favour of' becomes 'for' (being for a particular cause).
'turning' says the letters should be written backwards.
'in' is an insertion indicator.
'coalmine' becomes 'pit' (I've seen this before).
'for' backwards is 'rof'.
'rof' put into 'pit' is 'PROFIT'.
(Other definitions for profit that I've seen before include "financial advantage" , "Use" , "Gain from employment of capital" , "bonus" , "Net gain after expenses" .)