Clear a number of deliveries will be required before end of Test (5)
I believe the answer is:
overt
'clear a number' is the definition.
'overt' can be an answer for 'clear' (both can mean apparent or obvious). I am not sure about the 'a number' bit.
'of deliveries will be required before end of test' is the wordplay.
'of' becomes 'o''.
'deliveries' becomes 'ver' (I can't justify this - if you can you should believe this answer much more).
'will be required' means one lot of letters go next to another.
'before' means one lot of letters go next to another.
'end of' says to take the final letters.
The last letter of 'test' is 't'.
'o'+'ver'+'t'='OVERT'
Can you help me to learn more?
(Other definitions for overt that I've seen before include "Not locked away" , "This is not hard to see" , "Trove (anag.)" , "not disguised" , "____ is able to be seen" .)