Estimates from the right assuming record increase (4,2)
I believe the answer is:
step up
'increase' is the definition.
('step-up' can be a synonym of 'increase')
'estimates from the right assuming record' is the wordplay.
'estimates' becomes 'puts' (as in 'the expert puts her height at 6 feet').
'from the right' shows that the letters should be reversed in order.
'assuming' means one lot of letters goes inside another.
'record' becomes 'ep'.
'puts' back-to-front is 'stup'.
'stup' enclosing 'ep' is 'STEP-UP'.
(Other definitions for step up that I've seen before include "Boost" , "Advancement (on a ladder or career)" , "Raise by stages" , "Come forward" , "Sudden increase (in rate, output, etc)" .)