Strange hobby — clue “small compartment” (9)
I believe the answer is:
cubbyhole
'small compartment' is the definition.
(I've seen this before)
'strange hobby clue' is the wordplay.
'strange' indicates anagramming the letters.
'hobby'+'clue'='hobbyclue'
'hobbyclue' anagrammed gives 'CUBBYHOLE'.
(Other definitions for cubbyhole that I've seen before include "Small compartment, room space" , "Snug enclosed space" , "Recess to contain miscellaneous objects" , "Place for keeping bits and bobs" , "Small enclosed space or room" .)