"The thinking woman is standing."
Translation:생각하는 여자가 서 있어요.
Yes, it is because 생각하다 is an action verb (to think) while 똑똑하다 is a descriptive verb ("to be smart"). Action verbs always get 는 while descriptive verbs get either -ㄴ or 은.
From the tips and notes of the Modifiers 1 lesson:
For a basic descriptive verb ending in a consonant we take the verb stem and add -은. 작다 → 작은
For a basic descriptive verb ending in a vowel, you simply add -ㄴ at the end of the syllable. 나쁘다 → 나쁜
Action verbs as well as 있다 and 없다 are much more straightforward to turn into modifiers than descriptive verbs. Simply take the verb stem and add -는.
가다 → 가는
서다 is a stative verb, which has the irregular progressive form of appending the 해체 form with 있다. Thus the appropriate present progressive verb is 서 있다.
Note that you can still form a progressive verb in the usual fashion (서고 있다) but the meaning shifts to "in the process of standing".