Guilty-seeming way to fall foul of the RSPCA? (7)
I believe the answer is:
hangdog
'guilty-seeming' is the definition.
(as in a hangdog expression)
'way to fall foul of the rspca?' is the wordplay.
I cannot quite see how this works, but
'way' could be 'hang' (hang is a kind of way) and 'hang' is found within the answer.
'of' could be 'o' and 'o' is found in the answer.
This explanation may well be incorrect...
(Other definitions for hangdog that I've seen before include "Shamefaced like suspended canine?" , "Dejected - ashamed (appearance)" , "Apparently embarrassed" , "Downcast (expression)" , "With a guilty look" .)