Driver allowed tablets to be hidden in spirit on way back (8)
I believe the answer is:
muleteer
'driver' is the definition.
(thesaurus)
'allowed tablets to be hidden in spirit on way back' is the wordplay.
'allowed' becomes 'let' (to let is to allow or permit).
'tablets' becomes 'ee' (I can't explain this - if you can you should give a lot more credence to this answer).
'to be hidden in' is an insertion indicator.
'spirit' becomes 'rum' (alcoholic spirit).
'on way back' says the letters should be written backwards.
'rum' back-to-front is 'mur'.
'let'+'ee'='letee'
'letee' going into 'mur' is 'MULETEER'.
(Other definitions for muleteer that I've seen before include "One driving obstinate animal" , "Driver of pack animals" , "Animal driver" .)