Muscle moving odd tile (7)
I believe the answer is:
deltoid
'muscle' is the definition.
(deltoid is a kind of muscle)
'moving odd tile' is the wordplay.
'moving' is an anagram indicator (letters are moved around).
'odd'+'tile'='oddtile'
'oddtile' is an anagram of 'DELTOID'.
(Other definitions for deltoid that I've seen before include "Large triangular muscle that covers shoulder and raises arm" , "Triangular shoulder muscle - old diet (anag)" .)