Nitrogen needed in cereals, rum and soap (8)
I believe the answer is:
cleanser
'soap' is the definition.
(I've seen this in another clue)
'nitrogen needed in cereals rum' is the wordplay.
'nitrogen' becomes 'N' (N is the chemical symbol for nitrogen).
'needed in' is an insertion indicator.
'rum' is an anagram indicator (rum can mean strange or unusual).
'cereals' with letters rearranged gives 'cleaser'.
'n' inserted into 'cleaser' is 'CLEANSER'.
'and' is the link.
(Other definitions for cleanser that I've seen before include "this can remove dirty marks" , "Facial care product" , "Purifying lotion" , "Lotion removing grime" , "Cleaning cream or lotion" .)