Introducing ship to frustrate the plans of reactionary (6)
I believe the answer is:
fossil
'plans of reactionary' is the definition.
'fossil' can be an answer for 'reactionary' (thesaurus). I am unsure of the 'plans of' bit.
'introducing ship to frustrate' is the wordplay.
'introducing' is an insertion indicator (some letters introduced or inserted into others).
'ship' becomes 'SS' (prefix in ship names eg SS Great Britain).
'to frustrate' becomes 'foil' ('foil' can be a synonym of 'frustrate').
'ss' placed inside 'foil' is 'FOSSIL'.
'the' acts as a link.
Can you help me to learn more?
(Other definitions for fossil that I've seen before include "Fogeyish old thing" , "Animal remnant preserved in rock" , "Prehistoric remnant" , "Remnant of life in a rock" , "Petrified relic" .)