East European possesses Sulphur and little explosive device... Flee! (6)
I believe the answer is:
escape
'flee' is the definition.
(escaping is a kind of fleeing)
'east european possesses sulphur and little explosive device' is the wordplay.
I cannot really see how this works, but
'east' could be 'e' (synonyms) and 'e' is found in the answer.
'european' could be 'e' (abbreviation e.g. EU) and 'e' is located in the answer.
'sulphur' could be 's' (synonyms) and 's' is located in the answer.
'device' could be 'cap' (cap is a kind of device) and 'cap' is found in the answer.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for escape that I've seen before include "Elude; leakage" , "'Break free, get away (6)'" , "Abscond, flee" , "Get free from confinement or control" , "Key < flight" .)