Uncalled-for heckles ending in distress (8)
I believe the answer is:
needless
'uncalled-for' is the definition.
(synonyms)
'heckles ending in distress' is the wordplay.
'heckles' becomes 'needles' (I've seen this in another clue).
'ending in' suggests the final letters.
The final letter of 'distress' is 's'.
'needles'+'s'='NEEDLESS'
(Other definitions for needless that I've seen before include "without provocation?" , "Superfluous" , "Unneccessary and unwarranted" , "Excessive" , "Unnecessary, avoidable" .)