Remains while chap has series of tests (5)
I believe the answer is:
ashes
'remains' is the definition.
(I've seen this before)
'while chap has series of tests' is the wordplay.
'while' becomes 'as'.
'chap' becomes 'he'.
'has' means one lot of letters go next to another.
'series of tests' becomes 's' (I can't justify this - if you can you should give a lot more credence to this answer).
'as'+'he'+'s'='ASHES'
Can you help me to learn more?
(Other definitions for ashes that I've seen before include "trees" , "Powders remaining after fire" , "Remains of the Yule logs?" , "Eng./Aus. cricket trophy" , "Residue form fires" .)