Colonel to slip and fall apart (8)
I believe the answer is:
collapse
'fall apart' is the definition.
(I've seen this in another clue)
'colonel to slip' is the wordplay.
'colonel' becomes 'col'.
'to slip' becomes 'lapse' (lapsing is a kind of slipping).
'col'+'lapse'='COLLAPSE'
'and' acts as a link.
(Other definitions for collapse that I've seen before include "downfall" , "Founder" , "Abrupt failure of function" , "Disintegration" , "Fall down as from weakness" .)