Timer at the ready, giving a warning (5,3)
I believe the answer is:
watch out
'ready giving a warning' is the definition.
I can't judge whether this defines the answer.
'timer at the' is the wordplay.
I cannot quite see how this works, but
'at' is within the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for watch out that I've seen before include "Be careful!" , "Be vigilant" , "this could make synchronisation difficult!" .)