Based on observation, claim pier suffered damage (9)
I believe the answer is:
empirical
'based on observation' is the definition.
(I've seen this before)
'claim pier suffered damage' is the wordplay.
'suffered damage' is an anagram indicator.
'claim'+'pier'='claimpier'
'claimpier' anagrammed gives 'EMPIRICAL'.
(Other definitions for empirical that I've seen before include "experimental evidence" , "established by trial" , "Established by experiment" , "Based on observation or experiment, not on theory" , "as observer" .)