Fireguards put up to protect carpenter's tool (5)
I believe the answer is:
auger
'carpenter's tool' is the definition.
(I've seen this in another clue)
'fireguards put up to protect' is the wordplay.
'to protect' indicates a hidden word (the answer is protected by the clue).
'put up' says the letters should be written backwards.
'regua' is hidden in the letters of 'fireguards'.
'regua' back-to-front is 'AUGER'.
(Other definitions for auger that I've seen before include "Tool with spiral point for boring" , "something that's boring" , "A drilling tool" , "Boring-tool" , "I bore" .)