Pointless warning causing fleas terrible panic (5,5)
I believe the answer is:
false alarm
'pointless warning' is the definition.
'false alarm' can be an answer for 'warning' (I have seen 'Unnecessary warning ' mean 'false alarm' so perhaps 'warning' could also mean 'false alarm'). I'm unsure of the 'pointless' bit.
'fleas terrible panic' is the wordplay.
'terrible' indicates an anagram.
'panic' becomes 'alarm' (alarm can mean panic or fear).
'fleas' with letters rearranged gives 'false'.
'false'+'alarm'='FALSE ALARM'
'causing' is the link.
Can you help me to learn more?
(Other definitions for false alarm that I've seen before include "Warning proving unnecessary" , "Panic over" , "unfounded scare?" .)