Clips of leaders cracking under the strain (4)
I believe the answer is:
cuts
'clips' is the definition.
(I've seen this in another clue)
'leaders cracking under the strain' is the wordplay.
'leaders' suggests taking the first letters.
The first letters of 'cracking under the strain' is 'CUTS'.
'of' is the link.
(Other definitions for cuts that I've seen before include "Axes" , "Incisions" , "Severs" , "Tears" , "Snubs" .)