Dentist's recommendation for fluoride deficiency (5)
I believe the answer is:
floss
'dentist's recommendation' is the definition.
(I've seen this in another clue)
'fluoride deficiency' is the wordplay.
'fluoride' becomes 'f' (this might be a standard abbreviation of which I'm unaware).
'deficiency' becomes 'loss ' (I've seen this before).
'f'+'loss'='FLOSS'
'for' is the link.
Can you help me to learn more?
(Other definitions for floss that I've seen before include "teeth cleaner" , "What dentist could recommend" , "advice of dentist?" , "A mass of silky fibres - dental?" , "Eliot's river" .)