Practical labourer at work carrying bit of shelving (5-2)
I believe the answer is:
hands-on
'practical' is the definition.
(I've seen this before)
'labourer at work carrying bit of shelving' is the subsidiary indication.
'labourer' becomes 'hand' (hand is a kind of labourer).
'at work' becomes 'on'.
'carrying' means one lot of letters go next to another.
'bit of' indicates taking the first letters.
The first letter of 'shelving' is 's'.
'on' after 's' is 'son'.
'hand'+'son'='handson'
(Other definitions for hands-on that I've seen before include "Giving personal attention (to)" , "Actively involved" , "Involving practical participation rather than theory" , "Involving direct practical participation" , "Practical, working something directly - or manually" .)