Getting behind installing insulation (7)
I believe the answer is:
lagging
This could be a double definition.
'getting behind' is the first definition.
(I've seen this before)
'installing insulation' is the second definition.
'lagging' can be an answer for 'insulation' (lagging is a kind of insulation). I am unsure of the 'installing' bit.
Can you help me to learn more?
(Other definitions for lagging that I've seen before include "dropping behind" , "Getting behind" , "job in the attic?" , "Wrapping used to prevent loss of heat" , "Insulating material" .)