Way Shirley cleaned out trunk (6)
I believe the answer is:
'way' is the definition.
(I've seen this before)
'shirley cleaned out trunk' is the wordplay.
'cleaned out' says to hollow out the word (remove centre letters).
'trunk' becomes 'stem' (I can't justify this - if you can you should give a lot more credence to this answer).
'shirley' with its centre taken out is 'sy'.
Can you help me to learn more?
(Other definitions for system that I've seen before include "Complex whole; method" , "Arrangement of parts functioning together" , "Method (for betting?)" , "Organised structure for arranging or classifying" , "Operating structure" .)