Shrink a quarter of the flooring a twelfth of a foot (6)
I believe the answer is:
flinch
'shrink' is the definition.
(synonyms)
'a quarter of the flooring a twelfth of a foot' is the wordplay.
'a quarter of the flooring' becomes 'fl' (I can't explain this - if you can you should believe this answer much more).
'a twelfth of a foot' becomes 'inch' (I've seen this before).
'fl'+'inch'='FLINCH'
Can you help me to learn more?
(Other definitions for flinch that I've seen before include "Draw back in shock" , "Shrink back (out of pain/fear)" , "Cringe" , "Recoil from pain, surprise etc" , "Wince or draw back in fear" .)