Quick to adjust a veil (5)
I believe the answer is:
alive
'quick' is the definition.
(I've seen this before)
'adjust a veil' is the wordplay.
'adjust' indicates an anagram.
'a'+'veil'='aveil'
'aveil' anagrammed gives 'ALIVE'.
'to' acts as a link.
(Other definitions for alive that I've seen before include "Animate, breathing" , "Still with us" , "Still in use, not dead" , "Extant" , "operative?" .)