They make it easier to see small mushrooms, turned over (5)
I believe the answer is:
specs
'they make it easier to see' is the definition.
(spectacles)
'small mushrooms turned over' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'mushrooms' becomes 'ceps' (I've seen this before).
'turned over' says the letters should be written backwards.
's'+'ceps'='sceps'
'sceps' in reverse letter order is 'SPECS'.
(Other definitions for specs that I've seen before include "Glasses (informal)" , "Do they help one to see" , "Detailed plan" , "Glasses (sl.)" , "Glasses (colloq.)" .)