A minor possibly trailing about like a sponge? (5)
I believe the answer is:
cakey
'a sponge?' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.
'a minor possibly trailing about' is the wordplay.
'a minor possibly' becomes 'key' (A minor is a musical key).
'trailing' means one lot of letters go next to another.
'about' becomes 'ca' (circa).
'key' put after 'ca' is 'CAKEY'.
'like' acts as a link.
Can you help me to learn more?
(Another definition for cakey that I've seen is " Stuck together".)