Relatives cooked tuna with salt (5)
I believe the answer is:
aunts
'relatives' is the definition.
(aunt is a kind of relative)
'cooked tuna with salt' is the wordplay.
'cooked' indicates an anagram (letters cooked into a new form).
'with' means one lot of letters go next to another.
'salt' becomes 's' (this might be a standard abbreviation of which I'm unaware).
'tuna' anagrammed gives 'aunt'.
'aunt'+'s'='AUNTS'
Can you help me to learn more?
(Other definitions for aunts that I've seen before include "Sally and others" , "Female relatives, usually older" , "Parents' sisters" , "Elderly female relations" , "relatively speaking" .)