Some locusts are small and affectionate (5)
I believe the answer is:
swarm
'some locusts are' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'small and affectionate' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'and' says to put letters next to each other.
'affectionate' becomes 'warm' (synonyms).
's'+'warm'='SWARM'
Can you help me to learn more?
(Other definitions for swarm that I've seen before include "Body of bees" , "Arrive in numbers" , "Horde" , "Crowd of e.g. bees" , "Move in large numbers like locusts" .)