Learn French: J'ai un doute parce qu'il conduit sans autorisation. - I have a doubt because he drives without authorization.

After the preposition sans (without), French usually drops indefinite articles (un, une, des) and partitive articles (du, de la). Just like in English, you attach the noun directly to the preposition, making it sans autorisation.

Is j'ai un doute the standard way to say 'I am in doubt'?

Yes! While in English you might say 'I am doubtful' or 'I am in doubt', French uses the verb avoir (to have) for this expression. You literally say 'I have a doubt'.

Which verb is conduit?

It is the present tense il form of the irregular verb conduire (to drive). The singular forms follow a simple pattern: je conduis, tu conduis, il conduit.

Could I use à cause de instead of parce qu' here?

No. You use à cause de (because of) when it is followed by a noun, like à cause de la pluie (because of the rain). Because il conduit contains a subject and a verb, you must use the conjunction parce que (because).