Blessed one and Bartland are seized by crack militant (7)
I believe the answer is:
hostile
'militant' is the definition.
(thesaurus)
'blessed one and bartland are seized by crack' is the wordplay.
'blessed one' becomes 'st' (abbreviation for saint).
'and' is a charade indicator (letters next to each other).
'bartland' becomes 'I' (where the crossword setter is 'Bartland').
'are seized by' means one lot of letters goes inside another.
'crack' becomes 'hole' (hole can mean a crack or fissure).
'st'+'i'='sti'
'sti' placed into 'hole' is 'HOSTILE'.
(Other definitions for hostile that I've seen before include "Aggressive" , "Antagonistic" , "Bellicose" , "Showing angry opposition" , "Belligerent" .)