Watching — not entirely sure cover is alongside weapon (12)
I believe the answer is:
surveillance
'watching' is the definition.
(thesaurus)
'not entirely sure cover is alongside weapon' is the wordplay.
I cannot quite see how this works, but
'cover' could be 'veil' (I've seen this before) and 'veil' is found in the answer.
'weapon' could be 'lance' (lance is a kind of weapon) and 'lance' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for surveillance that I've seen before include "Watch" , "Close observation" , "Covert observation" .)