Worker consuming tiny amount is expert on bodies (9)
I believe the answer is:
anatomist
'expert on bodies' is the definition.
'worker consuming tiny amount is' is the wordplay.
'worker' becomes 'ant' (worker is a type of ant).
'consuming' indicates putting letters inside.
'tiny amount' becomes 'atom'.
'atom'+'is'='atomis'
'ant' placed around 'atomis' is 'ANATOMIST'.
(Other definitions for anatomist that I've seen before include "Structural expert" , "Body expert" , "One studying bodies" , "one studies bodies" , "Biological expert" .)