Somehow isn't as rat-infested after sending out echoes intermittently (2,4,3,6)
I believe the answer is:
in fits and starts
'intermittently' is the definition.
(I've seen this in another clue)
'somehow isn't as rat-infested after sending out echoes' is the wordplay.
I cannot quite see how this works, but
'as' could be 'in' (I've seen this in other clues) and 'in' is located in the answer.
an anagram of 'rat' is 'tar' which is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Another definition for in fits and starts that I've seen is " with bursts of energy".)