Outspoken member of House of Lords gives support (4)
I believe the answer is:
'support' is the definition.
(pier is a kind of support)
'outspoken member of house of lords' is the wordplay.
'outspoken' indicates a 'sounds like' (homophone) clue.
'member of house of lords' becomes 'peer'.
'peer' sounds like 'PIER'.
'gives' is the link.
(Other definitions for pier that I've seen before include "such as you might see at the seaside" , "Load-bearing pillar" , "Seaside structure" , "Upright member" , "Coastal platform" .)