Serious way to get help (5)
I believe the answer is:
staid
'serious' is the definition.
(thesaurus)
'way to get help' is the wordplay.
'way' becomes 'st'.
'to get' means one lot of letters go next to another.
'help' becomes 'aid' ('aid' can be a synonym of 'help').
'st'+'aid'='STAID'
(Other definitions for staid that I've seen before include "Restrained (in character)" , "Sedate, unadventurous" , "Calm, respectable and unadventurous" , "Demure" , "Sedate, sober" .)