Secure bats bat no.1 (6)
I believe the answer is:
obtain
'secure' is the definition.
(synonyms)
'bats bat no 1' is the wordplay.
'bats' indicates an anagram (slang for mad).
'1' becomes 'I' (Roman numeral).
'bat'+'no'+'i'='batnoi'
'batnoi' anagrammed gives 'OBTAIN'.
(Other definitions for obtain that I've seen before include "Take possession of" , "Get or receive" , "Gain possession of" , "Get, procure" , "Get one's hands on" .)