Maiden and I trapped by bit of a cow, getting dirtier (7)
I believe the answer is:
muddier
'dirtier' is the definition.
('muddy' can be similar in meaning to 'dirty')
'maiden and i trapped by bit of a cow' is the wordplay.
'maiden' becomes 'm' (cricket abbreviation).
'and' is a charade indicator (letters next to each other).
'trapped by' means one lot of letters goes inside another.
'bit of a cow' becomes 'udder' ('udder' is part of 'cow').
'i' put inside 'udder' is 'uddier'.
'm'+'uddier'='MUDDIER'
'getting' is the link.
(Other definitions for muddier that I've seen before include "More confused" , "More obscure" , "Less clear" .)