Not at home in Tynemouth (3)
I believe the answer is:
out
'not at home' is the definition.
(I've seen this before)
'in tynemouth' is the wordplay.
'in' says the answer is hidden in the clue.
'OUT' can be found hidden inside 'tynemouth'.
(Other definitions for out that I've seen before include "In error" , "Elsewhere -- unfashionable" , "on sale" , "Free" , "Known" .)