Home department by the end of March is thorough (2-5)
I believe the answer is:
in-depth
'thorough' is the definition.
(I've seen this before)
'home department by the end of march' is the wordplay.
'home' becomes 'in' ('he's home' can mean 'he's in').
'department' becomes 'dept'.
'by' is a charade indicator (letters next to each other).
'the end of' says to take the final letters.
The final letter of 'march' is 'h'.
'in'+'dept'+'h'='IN-DEPTH'
'is' acts as a link.
(Other definitions for in-depth that I've seen before include "Detailed and thorough" , "Getting to the bottom of it" , "Thorough and intensive" , "Full" , "searching" .)