Overtakes rival but it's a mistake they say (5)
I believe the answer is:
lapse
'mistake they say' is the definition.
'lapse' can be an answer for 'mistake' (I've seen this in another clue). I'm unsure of the 'they say' bit.
'overtakes rival but it's a' is the wordplay.
I cannot quite see how this works, but
'a' is found in the answer.
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is found in the answer.
The remaining letters 'lps' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for lapse that I've seen before include "Fall from grace" , "Failing" , "Brief failure of judgement" , "Fall back" , "Temporary failure of judgment or concentration" .)