Blimey, time is up! Let's have an ice cream! (6)
I believe the answer is:
cornet
'let's have an ice cream' is the definition.
I can't judge whether this defines the answer.
'blimey time is up' is the wordplay.
'blimey' becomes 'cor' (I've seen this in other clues).
'time' becomes 'ten' (I've seen this in another clue).
'is up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'ten' back-to-front is 'net'.
'cor'+'net'='CORNET'
Can you help me to learn more?
(Other definitions for cornet that I've seen before include "Cavalry officer" , "Musical instrument - ice cream" , "Ice cream cone" , "Brass band instrument" , "Kind of trumpet or ice-cream holder" .)