Component of lens is supporting infrared (4)
I believe the answer is:
iris
'component of lens' is the definition.
'iris' can be an answer for 'lens' (thesaurus). I am unsure of the 'component of' bit.
'is supporting infrared' is the wordplay.
'supporting' is a charade indicator (letters next to each other) (in a down clue, some letters go below others).
'infrared' becomes 'ir' (I've seen this in other clues).
'is' put after 'ir' is 'IRIS'.
Can you help me to learn more?
(Other definitions for iris that I've seen before include "Murdoch in writing" , "Pupil's place?" , "Eye part or pretty flower" , "Rainbow - flag" , "plant with showy flowers" .)