Cross, stopping by, introspective (6)
I believe the answer is:
broody
'introspective' is the definition.
(I've seen this before)
'cross stopping by' is the wordplay.
'cross' becomes 'rood' (term for a crucifix).
'stopping' indicates putting letters inside (inserted letters stop or plug a gap).
'rood' inserted within 'by' is 'BROODY'.
(Other definitions for broody that I've seen before include "Morbidly thoughtful" , "Introspective" , "Ready to incubate eggs" , "Thoughtful, unhappy" , "Pensive" .)