Zeal making engineers turn five into a smaller number (7)
I believe the answer is:
fervour
'zeal' is the definition.
(I've seen this before)
'engineers turn five into a smaller number' is the wordplay.
'engineers' becomes 're' (Royal Engineers).
'turn' says the letters should be written backwards.
'five' becomes 'V' (Roman numeral).
'into' is an insertion indicator.
'a smaller number' becomes 'four' (four is a kind of whole number. I am not sure about the 'smaller' bit.).
're' reversed gives 'er'.
'er'+'v'='erv'
'erv' placed within 'four' is 'FERVOUR'.
'making' acts as a link.
Can you help me to learn more?
(Other definitions for fervour that I've seen before include "Heated feeling" , "Passionate feeling" , "Ardent intensity" , "Heat of emotion" , "Zeal" .)