One recording beer drinkers downing last of ale (6)
I believe the answer is:
'one recording' is the definition.
(cameras record footage)
'beer drinkers downing last of ale' is the wordplay.
'beer drinkers' becomes 'CAMRA' (Campaign for Real Ale organisation).
'downing' is an insertion indicator (to down food or drink is to swallow it quickly).
'last of' says to take the final letters.
The final letter of 'ale' is 'e'.
'camra' placed around 'e' is 'CAMERA'.
(Other definitions for camera that I've seen before include "Image recording apparatus" , "Common recording device for pictures" , "Picture taker" , "Device for recording images" , "Device for taking photos" .)