Turn over a hard bit of safety film (6)
I believe the answer is:
serosa
'film' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'turn over a hard bit of safety' is the wordplay.
'turn over' says the letters should be written in reverse.
'hard' becomes 'sore' (I've seen this before).
'bit of' says to take the initial letters.
The initial letter of 'safety' is 's'.
'a'+'sore'+'s'='asores'
'asores' reversed gives 'SEROSA'.
Can you help me to learn more?
(Other definitions for serosa that I've seen before include "Liner" , "Body membrane" .)