Harass spies beginning to turn (6)
I believe the answer is:
molest
'harass' is the definition.
(I've seen this before)
'spies beginning to turn' is the wordplay.
'spies' becomes 'moles' (mole is a kind of spy).
'beginning to' suggests taking the first letters.
The initial letter of 'turn' is 't'.
'moles'+'t'='MOLEST'
(Other definitions for molest that I've seen before include "trouble" , "Attack sexually" , "Maliciously interfere with" , "Fame" , "Plague" .)