Covering provided by thatcher, partly (3)
I believe the answer is:
hat
'covering' is the definition.
(hat is a kind of covering)
'by thatcher partly' is the wordplay.
'partly' indicates the answer is hidden within the clue (part of the clue is used).
'HAT' can be found hidden inside 'by thatcher'.
'provided' is the link.
(Other definitions for hat that I've seen before include "e.g. Pork pie" , "Item of headgear" , "Eg, bowler" , "Headwear" , "Head-covering" .)