Blue novel about marine in service (7)

I believe the answer is:

useable

'in service' is the definition.
(not out of service)

'blue novel about marine' is the wordplay.
'novel' is an anagram indicator (letters in a new or novel order).
'about' indicates putting letters inside.
'marine' becomes 'sea' (both can mean 'of the sea').
'blue' is an anagram of 'uble'.
'uble' placed around 'sea' is 'USEABLE'.

(Another definition for useable that I've seen is " deployed".)

I've seen this clue in The Telegraph.

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