Think outside of uniform heritage centre (6)
I believe the answer is:
museum
'heritage centre' is the definition.
'think outside of uniform' is the wordplay.
'think' becomes 'muse' (musing is a kind of thinking).
'outside of' says to hollow out the word (remove centre letters).
'uniform' with its middle removed is 'um'.
'muse'+'um'='MUSEUM'
(Other definitions for museum that I've seen before include "Eg, the V&A" , "Store of historical artefacts" , "Eg, Horniman or Ashmolean" , "exhibition centre" , "Victoria and Albert, say" .)