Fast ship unloaded on track (4)
I believe the answer is:
spry
'fast' is the definition.
Both the answer and definition are adjectives. Maybe there's a link between them I don't understand?
'ship unloaded on track' is the wordplay.
'unloaded' suggests removing the centre (the content of the word is unloaded).
'on' says to put letters next to each other.
'track' becomes 'ry'.
'ship' with its middle taken out is 'sp'.
'sp'+'ry'='SPRY'
Can you help me to learn more?
(Other definitions for spry that I've seen before include "Still able to move lightly and fast" , "Moving quickly and lightly" , "Sprightly" , "(Of an old person) lively" , "Far from doddering" .)