Inside restrains a neurotic lunatic (6)

I believe the answer is:

insane

'lunatic' is the definition.
('insane' can be similar in meaning to 'lunatic')

'inside restrains a neurotic' is the wordplay.
'inside' says the answer is hidden in the clue.
'INSANE' is hidden within 'restrains a neurotic'.

(Other definitions for insane that I've seen before include "Irresponsible" , "out to lunch" , "having a screw loose" , "off trolley" , "Mad, irrational" .)

I've seen this clue in The Telegraph.

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