American laid out insane sum for a secretary (10)
I believe the answer is:
amanuensis
'secretary' is the definition.
(I know that amanuensis is a type of secretary)
'american laid out insane sum' is the wordplay.
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'laid out' indicates an anagram.
'insane'+'sum'='insanesum'
'insanesum' anagrammed gives 'manuensis'.
'a'+'manuensis'='AMANUENSIS'
'for a' acts as a link.
(Other definitions for amanuensis that I've seen before include "secretarial post" , "who may work with dictator?" , "Literary assistant - scribe" , "stenographer" , "Secretary" .)